In the wireless communications, a wireless communication system based on a Fourth Generation (4G) protocol standard-Long Term Evolution (LTE) is applied more and more widely. An LTE protocol standard absorbs and adopts good proposals from numerous mainstream wireless communication equipment manufacturers, and thus the LTE protocol standard may be considered as a set of the good proposals. As a basis of an LTE system design, the LTE protocol defines each aspect of an LTE system in more detail, certainly including LTE downlink physical layer processing. In particular, generation and mapping rules of an LTE PSS are described in the LTE protocol standard in detail.
For description about the PSS physical layer processing, the LTE protocol mainly includes description about a PSS generation rule and a PSS mapping rule in the LTE.
Specifically, the LTE physical layer protocol makes a definition shown in formula (1) for the PSS generation rule:
                                          d            u                    ⁡                      (            n            )                          =                  {                                                                      ⅇ                                                            -                      j                                        ⁢                                                                  π                        ⁢                                                                                                  ⁢                                                  un                          ⁡                                                      (                                                          n                              +                              1                                                        )                                                                                              63                                                                                                                                        n                    =                    0                                    ,                  1                  ,                  …                  ⁢                                                                          ,                  30                                                                                                      ⅇ                                                            -                      j                                        ⁢                                                                  π                        ⁢                                                                                                  ⁢                                                  u                          ⁡                                                      (                                                          n                              +                              1                                                        )                                                                          ⁢                                                  (                                                      n                            +                            2                                                    )                                                                    63                                                                                                                                        n                    =                    31                                    ,                  32                  ,                  …                  ⁢                                                                          ,                  61                                                                                        (        1        )            
where a value range of NID(2) is {0, 1, 2}, a value of u is 25 when a value of NID(2) is 0, the value of u is 29 when the value of NID(2) is 1, and the value of u is 34 when the value of NID(2) is 2.
In formula (1), du(n) corresponds to a PSS sequence. It can be known from the value range of n that n corresponds to 62 Resource Element (RE) sampling points. According to a value of u, it can be known that a value of the PSS sequence is only related to NID(2), and the value range of NID(2) is {0, 1, 2}. As can be seen from the above, there are three different PSS sequences according to three different values of NID(2) respectively, and each sequence corresponds to 62 RE sampling points.
The LTE physical layer protocol makes a definition shown in formula (2) for the PSS mapping rule:
                                                        a                              k                ,                l                                      =                          d              ⁡                              (                n                )                                              ,                      n            =            0                    ,          …          ⁢                                          ,          61                ⁢                                  ⁢                  k          =                      n            -            31            +                                                                                N                    RB                    DL                                    ⁢                                      N                    sc                    RB                                                  2                            .                                                          (        2        )            
For frame structure type 1, a PSS is mapped onto the last Orthogonal Frequency Division Multiplexing (OFDM) symbols in timeslot 0 and timeslot 10. For frame structure type 2, the PSS is mapped onto the third OFDM symbols in subframe 1 and subframe 6. The following RE sampling points
      k    =          n      -      31      +                                    N            RB            DL                    ⁢                      N            sc            RB                          2              ,      n    =          -      5        ,      -    4    ,  …  ⁢          ,      -    1    ,  62  ,  63  ,      …    ⁢                  ⁢    66    ,
are configured to reserve REs and not transmit the PSS, that is, a mapping value of the REs is “0”.
The LTE physical layer protocol makes the definitions about the PSS on the basis of implementation of the PSS in the frequency domain, and with reference to the abovementioned definitions, a flow of implementing the PSS in the frequency domain, as shown in FIG. 1, includes Step 101 of: frequency domain processing including PSS generation and power control and RE mapping, specifically mapping of the PSS and mapping of other signals and channels; Step 102 of: frequency/time domain conversion, specifically Inverse Fast Fourier Transform (IFFT); and Step 103 of: time domain processing, specifically sequent caching of the IFFT.
If a PSS is implemented in the frequency domain according to the definitions of the LTE physical layer protocol, since RE mapping in the frequency domain is a process of mapping RE sampling points in series, certain time overhead may be generated during RE mapping in the frequency domain, and thus the time consumed by LTE downlink physical layer processing may further be prolonged. Therefore, how to improve processing efficiency of an LTE downlink physical layer link becomes a problem urgent to be solved.